TDA4VEN-Q1: SPI performance issues

Hello,

Most of the team is on vacation. Please expect delayed response.

Best regards,

Keerthy 

Hi Xie,

please also help to try below 2 way if the data is still not right

-1-

add function

udelay(xxx);

yield();

-2-

-#define cpu_relax() barrier()
+static inline void cpu_relax(void)
+{
+ asm volatile("yield" ::: "memory");
+}
+

Regards

Joe

Because of the holidays, responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

Hi Joe,

Our project's requirement is to transmit 4k bytes of data in 20ms. Currently, we have found that adding a delay in the mcspi_wait_for_reg_bit function can solve the problem of high CPU usage, but 20ms cannot complete the transmission of 4k bytes of data, resulting in data loss; If we don't add delay, 4k data can be transmitted within 20ms, but the CPU usage is very high, which seems to be a contradiction.

How can I solve the problem of high CPU usage in SPI drivers?

Regards.

Hi Praveen,

Is any update here?

Regards.

Hi jc,

Isn't interrupt mode helping here? If not, we should use DMA for transferring 4K bytes. 

Is below thread related? 

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1456314/tda4ven-q1-how-to-enable-mcspi-slave-mode-dma/5589564#5589564

Regards,

Brijesh

Hi Brijesh,

Brijesh Jadav said:

Is below thread related? 

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1456314/tda4ven-q1-how-to-enable-mcspi-slave-mode-dma/5589564#5589564

 Yes, these two threads are related. The main purpose is to solve the problem of high CPU usage caused by SPI being the master, and to understand some implementations of SPI being the slave, in preparation for other projects in the future.

Regards.

Hi JC,

I think we have enabled DMA mode in SPI in the last release, but its enabled on RTOS driver, I am not sure about Linux. Any possibility of using RTOS driver for this? 

Regards,

Brijesh

Hi Brijesh,

The block diagram is as follows.I don't think using rtos driver is the solution we expected. SPI data ultimately needs to be provided to application algorithms for use on a53.

Will using rtos driver cause additional data latency (rh850-- (spi) -->rtos driver -- (ipc) -->a53)?

Regards.

Hi jc,

ok, that's one solution because i think DMA is supported in the RTOS in the last SDK release and yes the captured data can be transferred to A53 using IPC. 

I will check if/how DMA can be enabled in Linux driver. 

Regards,

Brijesh

Hi Brijesh，

Is the high CPU usage of SPI a known issue? Because I haven't found the same issue on other platforms(like xilinx sdk).

I hope you can find the way to enable dma in linux driver.

Regards.